SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58cc9dc49d69c1fcd84171418c76f3b31a15641b853ac36f486825691add1857' 
  AND token = 'KOzMpFX74guB8jnT0DiyPkNDXN+8MOPoFRXcbWFC3lo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}